The May 2012 Open-Source Radeon Graphics Showdown

Switching to the much more demanding idTech4-based Prey, the Catalyst
driver continued to blow away the competition. With the Radeon HD 5000/6000 series
when in the tweaked configuration, with 2D color tiling enabled, you see the frame-rates
go up significantly. While the frame-rates are up a lot, unfortunately this is
because the game was not rendering correctly on the open-source driver with 2D
color tiling for the HD 5000/6000 series.